Maud said it best. Now if you want, check out Smooth-Ons' Alginate, "Algisafe. It's usually about 50 bucks and it will get your head, neck, s houlders and prob. the majority of your chest done.
I just did a friends cast, and between the alginate, the mother mold, and the hydocal, I think it came out to 110 bucks - but he'll have it for ever as long as he takes care of it.